Force responsive tactile or contact sensors of a variety of types are known. In one type, such a sensor comprises a pair of sheets having confronting electrodes with a pressure sensitive material, such as a pressure sensitive resistive material, between sensing zones thereof. Patents showing such constructions include Published UK Application No. GB 2115556A and U.S. Pat. No. 4,856,993. Another patent disclosing available force sensor constructions is U.S. Pat. No. 5,398,962.
All of these sensors typically utilize a pair of confronting electrodes in which one of the electrodes is on one sheet and the other is on the other sheet. When there are multiple sensing zones, an array of one set of electrodes is provided on one backing sheet and a second set of electrodes is provided on the other sheet. These sheets must be prepared, as by printing, and must then be aligned carefully, one with the other, to make certain that all of the pairs of sensing zones and sets of electrodes are properly aligned.
Furthermore, because of the manner in which these force sensors are made, typically by silk screening, it is expensive to set up screens and patterns. Each different sensor requires its own special set of screens to produce the desired force sensor product. Where it is desired to make a sensor which is universal to a variety of alternative constructions, but without rendering active all of the sensing sites, that is virtually impossible to accomplish in any practical sense.
Accordingly, it would be desirable to provide a force sensor construction in which universality to a variety of configurations of sensor arrays is possible, while limiting completed circuits to only selected circuits and selected electrodes. It would also be desirable to provide a multi-electrode sensor construction in which most of both sets of electrodes are disposed on one of the two confronting backing sheets, thereby to minimize alignment requirements.